1. Field of the Invention
The present invention relates to a lossless encoding and decoding system, and method therefor, and more particularly, to a lossless encoding and decoding system including a lossless encoding apparatus and a lossless decoding apparatus in which encoded data can be decoded on a real-time basis.
2. Description of the Related Art
In general, a digital audio signal is obtained from an analog audio signal by means of a pulse code modulation method, in order to represent audio information with the number of channels, the number of bits and a sampling frequency according to DVD-audio standards. However, since a digital audio signal includes redundancy data, it is required to use lossless compression encoding methods, in order to shorten a recording time of a digital audio signal with respect to a digital versatile disc (DVD) and improve a bitrate.
A representative example of lossless compression encoding methods is the Huffman coding method, in which input data having a higher frequency of occurrence is assigned with a relatively shorter length of codeword and input data having a lower frequency of occurrence is assigned with a relatively longer length of codeword. In the case that a digital audio signal is losslessly compressed by the Huffman coding method, it is more efficiently coded than in the case that only a linear pulse code modulation (PCM) method is used.
Meanwhile, a predictor is used in the case that input data has predictable properties. The predictor determines prediction data corresponding to new input data using previous input data, and then uses a method for compressing a difference between the prediction data and the new input data. In the case that such a predictor is additionally used in the above-described lossless compression unit, an encoding efficiency with respect to the digital audio signal can be further enhanced.
When the above-described conventional lossless encoding method is used, a bitrate of the encoded data varies according to the degree of the property and randomness of input data, although a bitrate of the input data is constant. Thus, since conventional lossless coding methods require a very large capacity of buffers, in the case of data compression and decompression, it is difficult to encode or decode data in real-time. In addition, although a buffer capacity is increased in order to solve the above problem, a delay in decoding still remains.